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rweigel / cdawmeta

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Feature request: Documentation for CDF time data types #20

Open rweigel opened 2 months ago

rweigel commented 2 months ago

In the HAPI metadata, we want to include a note stating what CDF type the Time variable was derived from and also want to point the user to more information about interpretation (e.g., UTC based, etc.) We don't want to write our own explanation because of the experience we had with some SPASE records where a rephrasing of a source led to ambiguity or incorrectness.

A Google search of CDF_EPOCH16 shows mostly source code mentioning CDF_EPOCH16. The second page shows https://ui.adsabs.harvard.edu/abs/2011AGUFMSM21A2001C/abstract

It would be helpful if there was an authoritative link we could point to for the explanation. At present, we point to https://spdf.gsfc.nasa.gov/pub/software/cdf/doc/cdf390/cdf390ug.pdf, which contains a description, but this link may change; also, pointing to a 165-page document when the reader wants one sentence does not seem sensible.

Maybe post the poster https://ui.adsabs.harvard.edu/abs/2011AGUFMSM21A2001C/abstract, which I assume contains all the details, on Zenodo?

candeynasa commented 2 weeks ago

The 2011 Fall AGU poster SM21A-2001: "Common Data Format (CDF) New Time Variable CDF_TIME_TT2000" is now at https://spdf.gsfc.nasa.gov/pub/documents/SPDF/presentations/CDF_AGU2011_Common-Data-Format-CDF-New-Time-Variable-CDF_TIME_TT2000a.pdf . It's basically the info at https://cdf.gsfc.nasa.gov/html/leapseconds.html and https://cdf.gsfc.nasa.gov/html/leapseconds_requirements.html and in the CDF User Guide permanent link https://spdf.gsfc.nasa.gov/pub/software/cdf/doc/cdf_User_Guide.pdf . We're redoing the CDF website and can add a page on CDF variable types, pad values and typical fill values, and special time strings and their corresponding values.